Fix bug in dataset upload where the datastore uri was discarded (#9436)

This broke dataset upload if the datastore uri wasn’t equal to the wk
uri.

### Steps to test:
- Follow steps in
https://github.com/scalableminds/webknossos/wiki/Set-up-a-standalone-datastore-locally
- Upload a dataset via UI
- Should work.

------
- [x] Added changelog entry (create a `$PR_NUMBER.md` file in
`unreleased_changes` or use `./tools/create-changelog-entry.py`)
- [x] Removed dev-only changes like prints and application.conf edits
- [x] Considered [common edge
cases](../blob/master/.github/common_edge_cases.md)

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: Tom Herold <tom.herold@scalableminds.com>

Author: 3 people

frontend/javascripts/libs/resumable-upload.ts

@@ -248,7 +248,7 @@ const helpers = {
       url.searchParams.append(key, value);
     });
 
-    return url.pathname + url.search;
+    return url.toString();
   },
 };
 

unreleased_changes/9436.md

@@ -0,0 +1,2 @@
+### Fixed
+- Fixed a bug in dataset upload where the datastore URI was discarded and requests were always sent to the WEBKNOSSOS base URI.